The efficacy of bone marrow transplantation to counteract the deleterious effects of chemotherapy and ionizing radiation has been well established during the past three decades. It has also been demonstrated that the administration of bone marrow in genetic immune deficiencies, aplasias and in a number of blood dyscrasias was successful. More recently marrow engraftment has been successfully applied for the correction of genetic and metabolic disorders of the immune system, and in thalassemia. A number of registries for typed bone marrow cells have now been established on a national and international basis. It is the consensus of the leaders in bone marrow transplantation that the time has come for a convocation to delineate current knowledge in the field and to determine proper future directions in research and therapy. In 1987, the International Society for Experimental Hematology will hold a meeting in Tokyo, Japan with a participation of more than 500 scientists and clinicians. Most of the participants conduct research in bone marrow transplantation or related experimental hematology or therapy. Concurrent with this meeting a symposium on "Future Directions in Bone Marrow transplantation" will be organized. The speakers will be leaders in the field of bone marrow transplantation who will address an audience of experts in laboratory and clinical hematology. The increasing important contributions by Japanese hematologists recently, adds additional significance to this symposium.